Restoring habitats In the Kevin Costner movie Field of Dreams the central character is told "if you build it, he will come". But an Australian study has shown that Hollywood philosophy doesn't hold true in the animal world.

The study, published in the Journal of Applied Ecology, shows the successful restoration of plant species at disturbed landscapes, such as mine sites, is not an effective indicator of whether wildlife will recolonise.

"Everyone from mining companies to regulatory authorities and restoration ecologists has been working to a 'build it and they will come' paradigm," says lead author Dr Romane Cristescu, a former PhD student at the University of New South Wales.

Instead her study shows the established belief that if you restore an area's plant diversity the animals that once lived there will return, does not always apply.

The finding has implications for regulatory codes around rehabilitation because this belief has led flora rehabilitation success to be used as a proxy for fauna recolonisation success.

However Cristescu says the research shows this is not a "robust assumption" and suggests codes should include return of fauna criteria as keys in evaluating success.

Cristescu says the recolonisation of disturbed landscapes by fauna is imperative to maintaining the ecological functioning of an ecosystem and biodiversity.

"These fauna can play a critical role in pollination and nutrient cycling," she says.

Habitats destroyed

Determining more effective measures of rehabilitation success is also vital because of the impact mining has on habitats and the lack of frameworks globally for mine closure rehabilitation.

For the study Cristescu and her colleagues focused on koala populations at a rehabilitated sand mine site on North Stradbroke Island, a large sand island in Queensland's Moreton Bay.

The miner, Sibelco, is only the second mining company in Australia to have reached an agreement with all stakeholders, including the government, regarding rehabilitation success criteria, says Cristescu. The company financed the project to better understand how fauna responded to rehabilitation.

Cristescu says the research team used the agreed criteria to measure flora quality and found those areas rated the best quality in terms of plants, more often than not, had no koalas using them.

"Koalas did come back to the rehabilitated areas," she says. [It's just] the best areas in terms of flora were not the best areas in terms of koalas. Koalas are obviously looking for something else."

Others affected

Although the study was not able to determine what factors influenced the return of the koalas, Cristescu says we "cannot underestimate the influence on species recolonisation of factors such as interactions with other species, social structure and behaviour or dispersal abilities".

She says species richness in food trees and tree canopy cover also seemed to have a positive effect on recolonisation.

While the study only examined koalas, it was likely other animals would be similarly affected though "obviously what influences a koala and a lizard would be totally different", she says.

Cristescu says this work highlights the need for mining companies to preserve areas and species in the areas not directly impacted by mining.

Cristescu has now been employed by Sibelco to look at recolonisation by other animal species and to determine what factors encourage the return of animal life.